We always contact the author whose work may have been plagiarized to see if they are indeed simply posting here under a different name. We're very aware that people post on different sites under different pen names, particularly when it comes to posting on a site like ours that has adult content.
We do investigate fully before we make a determination that plagiarism exists. If the author of the story we think was plagiarized does confirm that they are the author here, only writing under a different pen name, we note that in our records. We will advise anyone who contacts us that the story is not stolen.
Conversely, if the author advises us that they did not publish their story here under any pen name, we remove the stolen work and the plagiarist.
Same narratives, similar characters and similar scenes are sometimes to be expected when working within a fandom. However, if the content is unique to the original author, we would deem that to be plagiarism if we encountered it in a story published later by another author. If you have a specific concern, you can always email us at tos_team@adult-fanfiction.org with the details.